Variable drive transmission



Dec. 11, 1951 1.. M GIHON VARIABLE DRIVE TRANSMISSION [NVENTUR 4 Sheets-Sheet l LEONARD/14c 6/HON Filed March 3, 1947 SECTION 11 II ATTORNEY 4 Sheets-Sheet 2 8 lag 5&

INVENTOR ATTORNEY LEONARD Mc CIHON L M GIHON VARIABLE DRIVE TRANSMISSION w W g g Dec. 11, 1951 Filed March 3, 1947 Dec. 11, 1951 MGGIHQN VARIABLE DRIVE TRANSMISSION 4 Sheets-Sheet 5 Filed March '3, 1947 MAW MOTOR LEONARD Me 611-! ON INVEN TOR BY 4/4;

ATTORNEY Dec. 11, 1951 L. Mo

VARIABLE DRIVE TRANSMISSION 4 Sheets-Sheet 4 Filed March 3, 1947 LEONARD McGIHON JNVENTOR ATTORNEY Patented Dec. 11, 1951 VARIABLE DRIVE TRANSMISSION Leonard McGihon, San Leandro, Calif assignor to King Sales & Engineering Co., San Francisco, Calif., a corporation of California Application March 3, 1947, Serial N 0. 731,964

12 Claims.

This invention relates to variable drive mechanisms and is concerned more particularly with an improved mechanism of this character which provides for a variable speed ratio between a source of power such as an electric motor and a driven mechanism.

It is a general object of the invention to provide an improved variable drive mechanism in which selected basic speed ratios can be employed and with respect to which the drive can be variable through a, selected speed range.

Another object of the invention is to provide a variable drive mechanism of the above character which occupies a small space and which provides a large amount of drive transmitting surface engagement for the given space.

Another object of the'invention is to provide a variable drive transmission which can employ conventional V-belt pulleys as the driving and driven members together with an adjustable drive transmitting element extending therebetween.

A further object of the invention is to provide a variable drive mechanism in which the varia-- tion of the drive is controlled by wrappingvariable amounts of a flexible drive transmitting element around the driving or driven pulley of the mechanism.

The above and other objects of the invention will be apparent from the following description of a certain preferred embodiment thereof as illustrated in the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view through a drive mechanism embodying the invention, the view being indicated by the line I--I in Figure 2.

Figure 2 is a transverse sectional view of the mechanism as indicated by the line II--II in Figure 1.

Figure 3 is a fragmentary'elevational view of a portion of one of the flexible drive members.

Figure 4 is an enlarged view of the upper portion of Figure 2.

Figure 5 is an elevational sectional view of the drive connection in an unfiexed or straight condition.

Figure 6 is a diagrammatic view illustrating a modified construction of the drive transmission.

Figure 7 is a sectional elevational view of a modified form of the drive mechanism in which both the driven and driving pulley mechanism have associated therewith adjusting means for controlling the length of the drive transmitting element to be wrapped thereabout,

Figure 8 is a horizontal sectional view or the mechanism shown in Figure '7, taken as indicated by the line VIII-VIII therein.

Figure 9 is an elevational view of a modified form of drive transmitting element.

Figures 10 and 11 together show transverse sectional views through a modified form of the variable drive mechanisms, the plane of the views being indicated by the line XIXI in Figure 12.

Figure 12 is a sectional elevational view of the form of drive mechanism shown in Figures 10 and 11.

Figure '13 is a fragmentary plan view of the mechanism shown in Figures 10 through 12.

Referring first to Figures 1 through 5, the variable drive mechanism includes a housing In of any suitable construction in which respective driving and driven shafts II and I2 are journalled. The driving shaft l l (Figures 1 and 2) has keyed thereon a multiple groove V-belt pulley I3 which in the present instance is shown as having four annular grooves of the usual form. The driven shaft l2 carries a similar multiple pulley H which, as shown, is one-half the diameter of the pulley l3 so that a two to one driving rela- I tionship between these two pulleys forms a basic speed ratio of the drive mechanism.

Associated with the respective driving and driven pulleys is an articulated drive connecting means trained thereabout indicated generally at 16 which is composed of a pair of chains carrying therebetween a corresponding series of V-belt segments or drive sections for cooperation withthe pulleys l3 and [4. In the present instance each of the respective chains l1 (Figures 3 and 5) includes a series of articulated links Ila of conventional construction which have associated therewith hinge pins of special construction. One set of alternately arranged hinge pins I'Ib extend outwardly with respect to each of the chains H, as seen in Figure 2, and each pin l'lb has secured thereon a conical control element I8. The other alternate series of hinge pins l'lc are common to the two chains l1 and intermediate these chains carry a series of V-belt segments IS. The segments l9 may be formed of rubber, either natural or synthetic, or a rubber fabric of the type commonly employed for V-belts, and the segments are molded about a journal or support portion I 9a having an upper arcuate belt bearing portion i917 provided for a purpose later referred to.

From the above description it will be seen that the drive connection I 6 by virtue of the drive transmitting segments l9b provides the drive characteristics of a V-belt while by virtue of the supporting chain construction the drive connection is articulated so that relative flexing can occur between adjacent links of the chain, as shown, for example, in Figures 1 and 3. The straight or unflexed condition of the drive connectionis .showndnFigure 5.

In order to vary the speed ratio' of thedrive-in selected limits with respect to the pre-selected basic drive ratio, the drive connection can be selectively articulated as it feeds onto the driving pulley l3 so that a greater lengthiofthezdrivecom nection can be wrapped around thisdrive pulley and in effect increase the speedtdriveof ithe-driven pulley I4 where the links are trained aboutii'n'unflexed or straight relation. In order to accomplish this control, the control'cones lflw-hich are disposed on alternate hinged joints of the.re.--.

spective chains are adapted to cooperate with respective opposite control cam wheels 21 having conical control surfaces 21a; The control wheels '21 'arejourna'lled freely, 'onfthe driving, shaft H andnre provided with grooved'collarsfl bwhich are" engaged by theforked 'ends of respectivecontrol forks 22 respectivelyipivoted-at'fi within the casing I'll. Thelower'end of each control fork 22 is pivoted at 14130 an internally threaded control sl'eeyeZG j iThetrespective sleeves '26 engage frespectivelywithcontrcl worms 2 l and-'28 secured .on a control" shaft 29 having .an operating handle 31 thereon. The respective worms 2'1 and 28 are threaded oppositely so that rotation of the shaft 29' and "the worms 2T'and 28 will effect simulta- .neous ln-and outmovement of'bothoi the control wheels 2|. The wheels 2 l' are shownin'their innermo'stip'ositionsin 'Figures 2 and 4 so that the alternate hinge joints lg'lb about the driving ele-- ment 1 3.'occ ,py their maximum radially displaced ,psitions,,and the greatest effective length of the drive connection is wrapped aboutthe drive pulw .In order to maintain the proper driving relationshlp of the, drive segments I9b' with the 'd'rlving jpulley l3, a hugbelt 3'6'is providedwhichis trained 'about'iouridler'rollersr3Tsuitably mountedi'nthe casing so thatflthe hug belt-encom- {passes approximately"oneehalffiof the pulley l3 and engages the sections: Nb of the drive transmitting segments .so that the segments I'B are maintained. in the desired driving relation-"with the pulley I 3'.

For accommodating the varyingjlengthof the drive connection IBin. diilerent conditions of .adiustment,- a suitable form. of slackrtake-up means may heprovidedjfor. example, 'theroller. 38journalledonawei'g'htedarm 39 pivoted at H on the casing, '10, IIf'.pref erred,,.a lspring-urgedroller ,3'8 may beflemployedinstead'ofa weighted'roller.

As shown in Figures. 1 and'l2, the control ele- .ments on conesil are disposedin their maximum inwardly,- adjusted position so that.the: .porti'on of .chaindrive element, inengagement. with the drivingpulleys 'l'lhasits linksflexed to themaxinumeso. that a ,maximumramcunt of this element 1S: wrappedv about the drive pulley performing theudrive andlthehighestspeed of operation of the driven pulley H isrobtained. It will. be noted that, as each successive aligned pair .of control cones Won the drive. connection engage the cooperatingrcontrol wheels 21, they are moved radially outwardly with respect to the pulley l3 while the drive transmitting segments l9v onvthe other alternateseries of hinged. joints of the chamsrpass beneath the hugbelt 3,6. Correspondingly, when the control cones l'8'leave the control cones 2|, the links of the chains are straightened so that the overall lengths of the drive connection for a given setting is not variable. Thus, by appropriate adjustment of the axial position of the control cones 2| with respect to the drive connection the speed ratio of the drive can be varied. Assuming ,that. the maximum.selected adiustment or angularityofgthe linkswheng-flaxedis at 45, the effective increase in length of the chain wrapped about the driving pulley is in the ratio of two to the square root of two. This is equivalent of changingthediameter of the pulley l3 by the same ratio in so far as its effect on the speed ratio of, the drivefisconcemed.

Inthejorm oi'the invention shown in Figure 6 the hug belt 36a is trained directly around the drive transmittingelement I8 and about a pair of idler rollers 31a disposed to the right of the driven pulley I' l so that the bug belt encompasses the entire drive mechanism. If desired, one of the rollers 31!: maybe made adjustableto compensate for stretchinthe belt'36a:

=In "theform-of the invention shown id-Figures "7 and-8, bothof-thedrivinrand driven pulleys-NI and 12- have associated therewith the respective pairs of adjusting cone wheels-liand Hwhich are reversely'adjustable'with'respectto eachother by means of 1 a pair 'ofdculile end 'controlforksflfi respectively; pivoted at 41. Each of 'theiorks 46 is 'apertured adjacentits'pivot'pointto receive oppositepivottrunnionslfioifanadiustmg-nutfl so: "that the angular position of the control forks 46 can be varied by means of the oppositely tiireaded wormsi-l' and'flcrn-the control shaft. "Inthis-inStancethe hug belt'flisftrained directly about the drivetransmitthigconnection: It. 'As shown; the-twodriving and drivenpulleyslhand 42 are of the'same diameter; but it a 'difleren't" diameteriis desired then the 'hug'belt would have associated therewith. a suitable Ltorm oi. takerup rollers'imilart'o that'shown 'at 38"in' Figure 1'.

From theabove description it will be .seenthat *by adjustmentEofthe-ccntrol'forks liamitherespective-sets of control-elements arcane wheels #3andiHi"the-amcunt-ciichainwrappedaboutthe respective driving and driven pulleys '41 andfl can be simultaneously-varied:

Figure 9 shows a modified form of-drive transmittingelernent in'-'which the' drive transmitting segments 6] (similar to the segments I!) are connected adjacent' eachend by respective pivot pins '6? to the adjacent chain links 53 so" thatias tension is applied to the drive connection the flexible drive segment fll tends to curve to ilt the circumference of thedriving-pulleywith which it i'S engaged.

Figures 10 through 13 illustrate a modified-form cf-"driveftransrnission in*w'h'ichthe controlmember for-eifecting' the flexing-adjustment 'of the drive chain is provided in the form of respective endless cam belts TI" and -II, provided with inclined innericam surfaces lilaand 12a, respectively, for cooperation with the 'contro'lcones or rollers l3 carried on alternate pivot pins 'Hofth'e drive chain. Withth'isiorm oi'the invention the effective wrapping of a greater length of the chain about the pulley is eflected by an exterior control with respect to the controtcones 1-3" on the drivetransm'ittingchain, and the forces exerted in effe'c'tingthis control also tend to keep the drive transmitting segments 16 engaged with the drive pulley l1. 'The'respective belts H and '12. are trained about r'e'spectlve. pulleys", each having an annular groove 19 to receive -a rib 81 of the cooperating belt; There are pulleys T8 on sired, each of the belts H and 12 may have a suitable spring-urged take-up roller 81 associated therewith.

In connection with the operation of the various modifications disclosed herein, it will be noted that each of them incorporates a flexible or articulated drive belt operating in conjunction with pulleys of fixed diameter, and that the change in speed of the driven member, for example pulley in Figure 1, is effected by wrapping more or less length of the drive connection or belt about the pulley in a given unit of time. The length of belt wrapped around the pulley M in a given unit of time is controlled by the flexing or zigzag positioning of the belt in travelling about the driving pulley l3. The cone-shaped control wheels 2! (Figure 2) serve to lift alternate pivotal connections of the links of the belt (see Figure 3) to place more length of belt about the pulley l3 in a given length of time than with the belt unflexed. This operation gives the same result with respect to the driven pulley M (increase in speed) as if the diameter of the pulley 13 had been increased.

While I have shown certain preferred embodiments of the invention. it will be understood that the invention is capable of variation and modification from the form shown so that its scope should be limited only by the scope of the claims appended hereto.

I claim:

1. A variable drive mechanism including respective drive and driven members of constant pitch diameter, an articulated drive element trained about said members having drive segments at a series of the points of articulation thereof and having control elements at another series of the points of articulation thereof, and control means for displacing said control elements radially of one of said members to effect zigzag flexing of the element as it travels about said one member to vary the speed ratio of the drive.

2. A variable drive mechanism including respective drive and driven members of constant pitch diameter, an articulated drive element trained about said members having drive segments at a series of the points of articulation thereof and having control elements at another series of the points of articulation thereof, control means for displacing said control elements radially of one of said members to eifect zigzag flexing of the element as it travels about said one member to vary the speed ratio of the drive, and means for engaging said drive element at said first series of points of articulation to maintain said drive segments engaged with said one memher.

3. A variable drive mechanism including respective drive and driven members of constant pitch diameter, and a flexible drive element trained about said members; said drive element comprising a pair of parallel chains, a series of common pivot pins extending between said chains, drive segments carried by said pins for engaging said members, each chain having another series of pivot pins projecting away from the other of the chains, and flexing control elements carried by said another series of pivot pins.

4. A variable drive mechanism including respective drive and driven pulleys of constant pitch diameter, and a flexible drive element trained about said members; said drive element comprising a pair of parallel chains, a series of common pivot pins extending between said chains, V-shaped drive segments carried by said pins for engaging said pulleys, each chain having another series of pivot pins projecting away from the other of the chains, and flexing control elements carried by said another series of pivot pins.

5. A variable drive mechanism including respective drive and driven pulleys of constant pitch diameter, and a flexible drive element trained about said members; said drive element comprising a pair of parallel chains, a series of common pivot pins extending between said chains, a plurality of parallel V-shaped drive segments carried by each of said pins for engaging said pulleys, each chain having another series of pivot pins projecting away from the other of the chains, and flexing control elements carried by said another series of pivot pins.

6. A variable drive mechanism including a drive member, a driven member, an articulated drive connection trained about said members, alternate pivotal connections of said drive connection carrying respective control elements for varying the radial position of the associated pivotal connection with reference to the associated member and the other alternate series of pivotal connections carrying drive elements engaging said members, and axially movable rotatable control means for engaging the control elements as they approach one of said members to cause flexing of the drive connection as it engages one of said members.

7. A variable drive mechanism including a drive member, a driven member, an articulated drive connection trained about said members, a series of pivotal connections of said drive connection carrying respective control elements for varying the radial position of the associated pivotal connection with reference to the associated member and another alternate series of pivotal connections carrying drive elements engaging said members, and adjustable control means for engaging the control elements as they approach one of said members to cause flexing of the drive connection as it engages one of said members.

8. A variable drive mechanism including a drive member, a driven member, a flexible drive connection trained about said members, a series of spaced control elements on said connection for causing flexing of the drive connection with reference to one of said members, and axially movable rotatable control means for engaging the control elements and causing flexing of the drive connection as it engages said one member.

9. A variable drive mechanism including a drive member, a driven member, an articulated drive connection trained about said members, alternate pivotal connections of said drive connection each including a control element for varying the radial position of the associated pivotal connection with reference to the associated member, axially movable control means for engaging the control elements and causing flexing of the drive connection as it engages one of said members, and means engaging the other alternate series of pivotal connections of said drive connection for maintaining the radial position thereof.

10. A variable drive mechanism including a drivevmemben. a driven membmeanj ertiaula ted driv conn ction. tramed. abmmsald: va flriesof the pivqtel.canneptionsp osaid dr e o neqtion each includin a co trol.- emen o va n th f e ive. l ngthof th HdI' ODBQQ? tion, and ont m ansfo eng theweqnr trol elements andehanging the efieetive length of the-drive connectionasitengages one=of members.

11. A drive oormeeizion mpniprisirkg 231! of spaced apart endless support ohains-, a seriesof utwa dl project nev ontml elemen soneachaot said cha ns. and r rieso r cros -e ements-exi d s e een sa hains, each: of said cr ss elements carrying at leastone-drivetransmitting 1 and drive receiving segment,

1 2. A variable drive mechanism; including -a, drive member. a, drivenmembena flexible drive eonnec iq rtram dabout said member a ois aped e ra lem tsLonls c n cf iqnz o musing, fl x ns hedrivefconnec ion h e erence to one of said members, and movableeont o eans for enga in he co o el me t n ca s ng flexinsnof the r ve con ect o s'it en gages said one member.

LEONARD McGIHON.

vREFERENCES CITED The following references are of recqrd'in the file Q r his patent;

UNITED STATES PATENTS N m r. Name Date 1,208,234 Ternstedt --vl Dec. 12, 1916 .581 56 Ca Kins.-.-.--.- June 8.. 92.6 1,656,628; Gif .-.M-.,. Jan. 17. 1928 

